Question
A rhombus shaped field has green grass for 18 cows to graze. If each side of the rhombus is 30 m and its longer diagonal is 48 m, how much area of grass field will each cow be getting?
Solution
For ΔABC
a = 30 m
b = 48 m
c = 30 m
Area of 
Area of the rhombus
= 2 Area of ΔABC = 2 x 432 = 864 m2
∴ Area of grass for 18 cows = 864 m2. ∴ Area of grass for 1 cow
Aliter : Draw BE ⊥ AC. Then E is the midpoint of AC.
In right triangle AEB.
AB2 = AE2 + BE2
I By Pythagoras Theorem ⇒ (30)2 = (24)2 + BE2
⇒ 900 = 576 + BE2
⇒ BE2 = 900 – 576
⇒ BE2 = 324
BD = 2 BE = 2 x 18 = 36 m Area of rhombus ABCD
Product of diagonals
Area of right 
∴ Area of rhombus ABCD = 4 Area of ΔAEB = 4 x 216 = 864 m2
∴ Area of grass for 18 cows = 864 m2
Area of grass for 1 cow = 
